Until this point, I didn't think high performance and factory side pipe covers went together. Let me say - kudos to Stahl Headers and Spiral Turbo Specialities (STS)! Both designed a new product using my car as a prototype. The punch line is 1 3/4" Stahl headers with split collectors into 3.5" tail pipes with shortened STS baffles... and, a balance tube. Photos and two video links at the end of this post.

I have always been a fan of the original factory side pipe covers on chrome bumper cars, but when I completed my last engine upgrade I thought I might not have a choice but to switch to rear exit exhaust to ensure I maximized my performance and maintained a reasonable sound quality. With the amount of money I invested in the 406, I didn't want to lose 70-90 hp through my existing exhaust (Hedman Headers into 2.5" pipes with dynomax chambered exhaust under the factory covers). I searched and searched and could not find anything I liked. Then I ran across Stahl and STS. These guys both spent a lot of time discussing combinations and design options with me over the phone - then I drove my car two hours to have Stahl use the car as a prototype to design a new set side exit headers.

To give an idea of performance... I drove the car 125 miles to Stahl. I have a Kiesler/Tremec 5 speed and I discovered on the drive up that my engine did not like 5th gear at all below 70 mph - I found myself constantly shifting between 4th and 5th gear. I was amazed on the way home that I was able to comfortably stay in 5th gear the entire way home - even below 65mph. Low end torque was significantly increased. On the top end, I was even more amazed. Seat of the pants says I got back at least 50-70 hp and the thing just wants to keep pulling over 6500 rpm - before it was running out of steam just over 6000rpm. I have flywheel dyno data, so I promised STS I would do some chassis dyno runs to provide data inputs - will post once I find a chassis dyno.

As for sound, I am running the baffles uncapped. Even still, the sound is no louder than my old chambered exhaust. The main difference is I have a whole new sound - much more "racey". For now, I will leave them uncapped. Stahl also made me a set of shortened race pipes, so I might cap the baffles to reduce sound and use the race pipes at the track.

Workmanship and quality of materials for both Stahl and STS was top notch. I have gained significant performance improvements and achieved a reasonable sound level (yes, it is loud, but can be quieted by capping the baffles or using a longer baffle).

Here are some photos and a video link (1st and 2nd gear to 6500 - 90% throttle with granny shifts... still running the original rear - don't want to break it before it has a chance to be rebuilt.)










http://s53.photobucket.com/albums/g5...t=107_0713.flv

http://s53.photobucket.com/albums/g5...t=107_0707.flv

 

Very nice I need something like that for a 502 BB. Wonder if they have one for that engine????

Bullshark

 

If they don't, they can make it - worth a call. They even do stepped headers for cars with raised port heads.

 

Those things really look sweet. But I would imagine not cheap?

 

No, not cheap, but considering the horsepower gain and smoothness of the torque curve, I would say worth it. I believe Stahl will be selling these headers somewhere around $1000 (does not include tail pipes and balance tube).

 

Looking forward to the dyno data as I'm planning on putting side pipes with the stock covers on my car.

 

DAYUMM! Those are SWEET! Impressive.

Now I gotta go out and buy a chrome bumper Vette to put them on.

-Mark.

 

I'll give this a bump. Can't believe nobody else is interested in this. I also have another question. You mentioned that they are loud. How is the resonance? I'm running Flowmaster 40s now. I don't have any problems with how loud they are but the resonance is driving me crazy.

Also, do you have any pics from the outside. I'm wondering how well the shields cover.

 

I need to take photos of the covers... I'll try to do that tonight. The only thing you see different is the 3.5" turnout poking out of the backside of the shield. It could be cut to be flush with the cover, but at the expense of horsepower... most would never notice. You really can not even tell they have been spaced 3/8".

As for the resonance - I really don't notice any... think the balance tube helped that. I do usually have the top down which reduces the impact of resonance, so I might not have a real good ability to judge. Just put the hard top on last week, but haven't really driven it yet.

 

I finally had a few minutes to take a few photos showing the pipes under the covers. I decided to take Stahl's advice for maximum performance and not trim the tips to fit flush with the cover opening. This is the only only part that does not appear stock. Dyno testing next......

 

why not cut the tips flush.....btw, that looks beautiful. Please give details of your springs/suspsension and fender lip height at the front/rear.

 

Thanks for the compliments RedShark! By the way, your car was one of the ones that inspired me to finally upgrade my wheels to 17". After seeing how good your car looked with them, I decided to go for it.

Distance from ground to front fender lip is 26 1/4" and rear fender lip is 26 7/8". At that height in the rear, my half shafts are perfectly straight into the rear and hubs, so it worked out well. I have the complete VB&P Performance Plus Suspension Kit. I keep the springs rates at the third hardest setting - using Bilstein shocks.

According to Stahl, shortening the pipe and cutting it at an angle to match the cover would significantly alter the flow of the exhaust. Seems hard to believe, but he was dead on with everything else he told me, so I trust it is true. He also made me a second set of short pipes that I can slip on for the track.

 

those things are amazing... if only I could afford them. I've wanted some of stahl's headers for a while now, but it looks like I'll go with a cheaper set for now.

 

is stahl making this complete setup for sale???????????????????????????????????? ????????????????????????

 

Going from Headman side exhaust headers to Stahl alone is a HUGE difference. Adding the cool quad(?) exhaust has gotta be way helpful.

Keith

 

Yes, Stahl used my car to completely redesign his set-up and it is for sale. I drove my car up to his shop in PA from Virginia and he and his guys spent a couple of weeks redesigning the headers and engineered the balance tube. I worked with Jim from STS baffles to complete the set-up, he shipped the baffles directly to Stahl.

 

This is definitely going to be my next major purchase. I think I will just paint the pipes flat black so they don't show under the covers as much. Thanks for the update, Witz!

 

this will be my next purchase...you can count on that!

 

man, just had to come back and look at that beautiful work again....

 

I just looked at them again and I agree that the workmanship is beautiful, but I thought you had 4 exhaust pipes, now I see that those long rear things are the corssover???

Sorry, but thats weird in my book, if it even helps being that long.

Shesh, might as well run them out the back if you are that close.